versperren
to block
To block a path, an access point, or a view so that one can no longer go through, get in, or see through.
Ein umgefallener Baum versperrt die Straße.
A fallen tree is blocking the road.

to block / to lock
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to block
To block a path, an access point, or a view so that one can no longer go through, get in, or see through.
Ein umgefallener Baum versperrt die Straße.
A fallen tree is blocking the road.

'versperren' (to block / to lock) is an inseparable verb. The prefix 'ver-' remains firmly attached to the verb stem in all tenses and sentence constructions and is never separated.
Er hat mir den Weg versperrt.
He blocked my way.
'versperren' (to block / to lock) is often used with three elements: who or what blocks something (subject), for whom something is blocked (dative), and what is blocked (accusative).
Der große Schrank versperrt uns die Sicht auf den Garten.
The large cabinet blocks our view of the garden.
The object of the sentence makes the meaning clear. If a path or a view is blocked, the first meaning is intended. If a door or lock is secured, the second meaning is intended.
Ein Unfall versperrt die Autobahn.
An accident is blocking the highway.
In the meaning of 'eine Tür abschließen' (to lock a door), 'versperren' (to lock) is used especially often in Austria and parts of southern Germany. There, it is an everyday word for this action.
Bitte versperr die Tür, wenn du als Letzter gehst.
Please lock the door if you're the last one to leave.
to lock / to complete
'abschließen' and 'versperren' can both mean that an entrance or access point is not open or cannot be used. 'abschließen' is used especially when you secure a door, gate, or room with a key or bolt. 'versperren' can also be used this way, but it often means more generally that something blocks the way, access, or view. This can be a lock, but also a car, a piece of furniture, or a fallen tree. Learners may confuse the words because both have to do with 'not being able to get in'. If a key is important, 'abschließen' usually fits better; if something is in the way, 'versperren' fits better.

Ein Lieferwagen versperrte am Morgen die Einfahrt zur Werkstatt.
In the morning, a delivery van blocked the entrance to the workshop.
Im Sommer schließen wir das Gartentor jeden Abend ab.
In summer, we lock the garden gate every evening.